Melting Arctic ice cap won't raise level of ocean waters

May 20, 2008|Arnold W. Schultz, Boynton Beach

Thursday's article, "S. Florida at risk of vanishing?" on the front page was amusing to me, if not unduly alarming. Apparently, the reporter's understanding of global warming, as it relates to the melting of the Arctic ice cap, is that the ocean level would rise. Many people have this same misconception. In fact, however, were the polar ice cap to melt, then you would experience a diminishing ocean level.

Let me explain: When water freezes, it expands by roughly 5 percent in volume. This is commonly observed in our northern states during the winter season as evidenced by the many potholes sprouting in the roadways. A very quick experiment to show that ice shrinks in volume when melting is to fill a glass with as much ice as you can and then fill the glass with water up to its brim. As the ice melts, you will observe that the water level in the glass decreases.

The polar ice cap is nothing more than a huge chunk of ice floating on water. As it melts, the water level will decline. However, ice sitting on land, such as on Greenland, or on Antarctica, is another matter. Were this ice to melt, then, yes, the ocean level would rise. But from what I have been reading lately, Antarctica is undergoing a growth spurt in its ice cover.